Track tilt control system for cranes



March ,-1 R. G. LE TQURNEAU 2,631,736

TRACK TILT CONTROL SYSTEM FOR CRANES Filed April 20', 1949 '& A

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ROBERTG. LETOURNEAU AGE/V Patented Mar. 17, 1953 UNITED: STATES TRACKTILT "CONTROL SYSTEMFORF CRANES.

Robert iG} Lee-Tourneau, Longview; Tcx assignor to zRaGaLeqTourneau, Inc.', Longview,;Tex:-, a corporation-0f California Application AprifZO, 1949; Serial N088594- ent invention to provide a--track tiltcontrol-system which performs-all of"the'funetions--of the previous invention but in a more-advantageous and economical manner.

Another object of this invention is-to-provide a control systembetween the track and'tongue' of i a crane: of thistype, which is cable-operated by means of'an electric winch; andin'which'the cable is the. only; connection between thetrack and tongue.

It. is alsoan objectLofthisinvention to provide a ,track. tilt. control Lsvstemin .wh'ichpthe heavy power, unit. for its. operation is, placed on the crane insucha, manner, that it's weightLconr tributesto .the balance. and traction. ofjthe ,machine..

It. is an additionalobjectmo .providea track tilt. control. system which includesia. structural frame which positionsthe.movablesheave ho.us-. ing at such a position relativeitosthe stationary,

sheavehousing thatqthere is suitable leverage available at all positions of operation.

A still further. objecti-offthis;invention is to provide a system. of this .typeinwhich the-structural frame on the track and. the sheave 11.01151 ing on the tongue contain cooperating stop means to prevent 'excessive movement-*of-the-track in a forward direction.

These. objects .I. accomplisngbyrmeansioiisuch structure zand .relativecarrangement of .par't'ssas will; fully-appear. by. a perusal of the-:following: specifications .and..claims:.

In the drawings similar characters of reference indicate corresponding parts in :tha-severa'l-wiews.

Fig. l is-aside'view ofa-craneembodying my improved tracktilt control -system.

Fig: 2 is a plan view of the movable sheayejand the stationary sheave "in operational alignment, but detached from the remaining structure.

Fig. 3 is a schematic showing of one limit switch wiring arrangement.

Referring now more particularly to the characters of reference on the drawing, a crane on which this system may be utilized is shown in outline in Fig. 1 to consist basically of a longitudinal tongue I attached to a two wheel tractor 2 2-3at1tits forward-lend by means of steering; 3 theatongue 11s zsupportedz-at: its rear end;,by'::a' rear Wheel "and *axle.zstructure .dzto which is; Div:.-v oted' a tilting: traclc: 5 containing:- an elevating:

boomv 6": with a depending-hook bioclcfl The:

method of 'pivotingtrack; 5::to the:reauaxlerstruce ture maybeeither oirthe-methodsshown inadea tail. in: my. previous Patents. 2;.444,'835:. and 2,394,314. Track. 5 :is. supported: 2.1151178 lowenend.

' by-bearing$.:26x on theaxle;2iffor tiltingadjusts ment of said track lengthwiseuoi the-.zimplemcnt: The track 5'.is..equipped-.;with zaepyramid-algframe 8 which supports.- and; positions movablet sheave; housingrBb at; the =desired1locationysothatrample;

-' leverage is available for tilting track. Seaboutxits.

pivot even when, thexboom dais. lying. on: the round:

A sheave thousingul 0 .is .positionedlon tongue; .i in alignment with housing 9;.and cable drum:

" of housing 9?. from whencecit passes toand is fixed .on .cablesanchor. 25: on the sideof sheave housing: l0:

Winch unit I2 is an electric motor-driven-unit which receives its power from .a genera-ton (Fig. 39' mounted on and driven by: thetractor 2'. Electric cable: I 4.. delivers .the electric current: to winch llwfrom thez switchbox [5 01": the-tractor.- This :winch-is controlled from an electric switch locatedton the: daslr panel' l8:- of the operators cockpit offthe tractor; Winch 'unit l2; beingoi substantial iweight; placed forward: onr tongue I? socas-.:to: counterbalance-a i portion of the load placed it on'; hook block: I I and also contribute: to

therztraction ors'wheels- !3s.0f tractor "2';

If frameB werernotz-included on track :5 there would; berthe. dangeryof. a... free:.=fa1l2 of track 5 and: boom; after they. passed: top dead center whenawmovingsinea forward direction. Frame 8 and stop z-blocksl. i Bret zsheava housings .9 ancl -llli prevent this fromzhappening: 'Iheweight: and ba1ance.=.;of tracka is sosarranged that :a: constant pull on" cable I? is necessary :to hring the two stop blocks together. However, if the operator kept his control switch depressed after the blocks had touched there would be a. danger of damaging the winch unit or breaking the cable H; to prevent this I have provided a limit switch 19 on sheave housing [0 to be operated by cam 20 of sheave housing 9 just prior to contact of the stop blocks I6. Electric cable 2! interposes limit switch I9 into the electric circuit of winch I2 in such a manner that when the plunger 22 of limit switch I9 is depressed, the electric circuit for rotation of the winch in a direction to reel in cable is broken; this prevents any further movement of sheave housing 9 in a direction toward housing I9. Rotation of the winch in the other direction is not effected and the track may be tilted backward whenever desired. When cam moves out of contact with plunger 22, the contact is again closed and the winch may then be rotated in either direction.

In ordinary operation the stop blocks I6 will never come in contact due to the presence of cam 20 and limit switch I 9. The tapered portion 23 of the cam will depress plunger 22 and thereby shut off current to the winch. However, under some circumstances, such as the dropping of a load from block I or the breaking of a hoisting cable, it is possible for the track and boom to come forward independent of the operation of winch I2. In these cases the cam 20 will slide by block I6 on sheave housing It] and the two stop blocks IE will come into abutment. This action provides an additional safety feature and will prevent damage to the machine and danger to the operator during these emergencies.

It will be noticed in Fig. 2 that housing I9 is set on the tongue I at a slight angle to the longitudinal center line of the machine. This was done to permit the relatively long winch I2 to have ample support from the tongue by mounting plates 24, and still permit the center line of cable drum I I to be in substantial alignment with sheave housing II].

From the foregoing description it will be seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a, departure from the spirit of the invention, as defined by the appended claims.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. In a crane having a tongue supported by a rear wheel structure and a track pivoted to the rear wheel structure for tilting thereabout in a longtudinal vertical plane, a track tilt control system comprising a pyramidal frame structure'including upstanding arms projecting a substantial distance from said track, a support member fixed to said structure at its apex, a plurality of sheaves and a sheave housing mounted on said member and movable with the track, a stationary sheave housing and a plurality of sheaves mounted therein fixed to the tongue in substantial alignment in a vertical plane with said movable sheave housing, a cable reeved between the sheaves of said housings, means for moving the movable sheaves and the track toward the housing fixed on said tongue, said means comprising said cable and a power winch mounted on the tongue adjacent the forward end thereof, cooperative stop means mounted on said sheave housings to prevent excessive forward movement of the track, said stop means comprising: corresponding stop blocks affixed to each sheave housing, electrical means including an electric circuit to power said power winch, and a limit switch on one of said housings and an actuating device on the other housing, the switch and the actuating device being mounted to come into engagement just prior to contact of said stop blocks to open the circuit to said power winch.

2. In a crane having a tongue supported by a rear wheel structure and a track pivoted to the rear wheel structure for tilting thereabout in a longitudinal vertical plane, a track tilt control system comprising a pyramidal frame structure including upstanding arms projecting a substantial distance from said track, a support member fixed to said structure at its apex, a plurality of sheaves and a sheave housing mounted on said member and movable with the track, a stationary sheave housing and a plurality of sheaves mounted therein fixed to the tongue in substantial alignment in a vertical plane with said movable sheave housing, a cable reeved between the sheaves of said housings, means for moving the movable sheaves and the track toward the housing fixed on said tongue, said means comprising said cable and a power winch mounted on the tongue adjacent the forward end thereof, cooperative stop means mounted on said sheave housings to prevent excessive forward movement of the track, said stop means comprising: corresponding stop blocks aifixed to each sheave housing, electrical means including an electric circuit to power said power winch, a plunger operated limit switch on one of said housings, a projecting bar having a cam surface on the other of said housings, the cam surface being operative to depress the plunger just prior to contact of said stop blocks to open the circuit to said power winch, said projecting bar being attached to one surface of one stop block, said limit switch being offset from the other stop block to the extent that said stop blocks will come in contact if forward movement of the track continues after contact of the bar and the limit switch.

ROBERT G. LE TOURNEAU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,369,165 Cochran et a1 Feb. 22, 1921 1,559,880 Ionides Nov. 3, 1925 1,694,084 Straight Dec. 4, 1928 2,058,473 Le Tourneau Oct. 27, 1936 2,096,186 Le Tourneau Oct. 19, 1937 2,375,800 Le Tourneau May 15, 1945 2,391,881 Clay Jan. 1, 1946 2,394,314 Le Tourneau Feb. 5, 1946 2,444,835 Le Tourneau July 6, 1948 2,529,193 Rueter Nov. 7, 1950 

